Our goal is to better define the etiology and pathogenesis of a naturally occuring acquired immunodeficiency syndrome in rhesus monkeys at the California Primate Research Center. This disease will be called "SAIDS" for simian AIDS. This monkey disease has many similarities (opportunistic infections, malignancies, immunodeficiency) to the acquired immunodeficiency disease syndrome (AIDS) currently reaching epidemic proportions in the human male homosexual population. SAIDS should provide an excellent comparative animal model which has been heretofore lacking for the human disease. The biology of this model system will be studied from a multi-disciplinary approach. Environmental and host risk factors will be defined. We will attempt to experimentally transmit the disease in a controlled laboratory setting and define the infectious agent(s) and routes of natural spread. Although other indigenous viruses will be monitored we will focus our efforts initially on the role of active infection with cytomegalovirus (CMV), highly prevalent both in SAIDS and AIDS. The natural history of CMV in relation to host immunity and disease will be examined in the affected and control monkey subpopulations. Tumors will be examined for non-productive infection with simian CMV and other latent viruses. Understanding this animal model should lead to a better way of coping with or preventing the human disease counterpart.